Jonas David M
Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, USA; email:
Annu Rev Phys Chem. 2018 Apr 20;69:327-352. doi: 10.1146/annurev-physchem-052516-050602.
Femtosecond two-dimensional (2D) Fourier transform spectroscopy generates and probes several types of coherence that characterize the couplings between vibrational and electronic motions. These couplings have been studied in molecules with Jahn-Teller conical intersections, pseudo-Jahn-Teller funnels, dimers, molecular aggregates, photosynthetic light harvesting complexes, and photosynthetic reaction centers. All have closely related Hamiltonians and at least two types of vibrations, including one that is decoupled from the electronic dynamics and one that is nonadiabatically coupled. Polarized pulse sequences can often be used to distinguish these types of vibrations. Electronic coherences are rapidly obscured by inhomogeneous dephasing. The longest-lived coherences in these systems arise from delocalized vibrations on the ground electronic state that are enhanced by a nonadiabatic Raman excitation process. These characterize the initial excited-state dynamics. 2D oscillation maps are beginning to isolate the medium lifetime vibronic coherences that report on subsequent stages of the excited-state dynamics.
飞秒二维（2D）傅里叶变换光谱法产生并探测几种类型的相干性，这些相干性表征了振动和电子运动之间的耦合。已经在具有 Jahn-Teller 锥形交叉点、伪 Jahn-Teller 漏斗、二聚体、分子聚集体、光合光捕获复合物和光合反应中心的分子中研究了这些耦合。所有这些都具有密切相关的哈密顿量和至少两种类型的振动，包括一种与电子动力学解耦的振动和一种非绝热耦合的振动。偏振脉冲序列通常可用于区分这些类型的振动。电子相干性会因非均匀退相而迅速模糊。这些系统中寿命最长的相干性源于基态电子态上的离域振动，这种振动通过非绝热拉曼激发过程得到增强。这些表征了初始激发态动力学。二维振荡图开始分离出报告激发态动力学后续阶段的中等寿命振动电子相干性。
